1. Field of the Invention
The present invention relates to a power tool, and more particularly to a power tool having a mechanism for automatically driving tool members in either of the driving directions.
2. Description of the Prior Art
Various kinds of typical power tools have been developed for driving tool members with motors or the other hydraulic or pneumatic driving mechanisms. Two examples of the typical power tools have been disclosed in U.S. Pat. No. 5,887,666 to Chen et al., and U.S. Pat. No. 6,283,226 to Chen.
The typical power tools comprise a shaft selectively operated by a motor in either of two driving directions. However, a number of parts or elements are required to be assembled together with shafts or rods and fasteners and will be disengaged from each other after high speed rotational operations.
In addition, the driving shaft and a number of parts, particularly some of the springs will be rotated in fast speed by the motor, such that the spring biasing forces of the springs will be decreased after use. However, the springs of the typical power tools may not be adjusted to different resiliences.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional power tools.
The primary objective of the present invention is to provide a power tool including a mechanism for automatically driving tool members in either of the driving directions.
The other objective of the present invention is to provide a power tool including an integral housing for stably receiving the pawl and the spring and the other parts or elements.
The further objective of the present invention is to provide a power tool including a spring that may be adjusted to different spring biasing forces against the pawl.
The still further objective of the present invention is to provide a power tool including a housing having an internal gear for engaging with the pinion of the motor and for allowing the housing to be solidly driving by the motor.
In accordance with one aspect of the invention, there is provided a power tool comprising a seat, a housing rotatably secured to the seat, and including an internal gear formed and provided therein, the housing including a bore formed therein, and including a notch formed therein and communicating with the bore thereof, a motor attached to the seat, and including a spindle having a pinion secured thereto and engaged with the internal gear of the housing, for driving the housing to rotate relative to the seat, a shaft rotatably received in the bore of the housing, and including two cavities formed therein and spaced from each other, a pawl rotatably secured in the notch of the housing, and including two ends caused to selectively engage with the cavities of the shaft when the housing is rotated relative to the seat by the motor greater than a predetermined speed, and means for biasing the ends of the pawl from the cavities of the shaft when the housing is rotated relative to the seat by the motor in a speed less than the predetermined speed.
The housing includes two walls having the notch formed between the walls, the walls each includes a hole formed therein, and a pin engaged through the pawl and having two ends engaged in the holes of the walls.
The cavities of the shaft are offset from each other, a first of the cavities of the shaft is located closer to the seat.
The seat includes an aperture formed therein, a collar engaged in the aperture of the seat, the shaft includes a rod rotatably engaged in the collar.
The biasing means includes a spring member secured to the housing for engaging with the pawl and for disengaging the ends of the pawl from the cavities of the shaft.
The housing includes a plurality of juts provided thereon, the spring member includes a first end selectively secured to either of the juts.
An actuator may further be provided and slidably engaged in the housing for engaging with the pawl to disengage the ends of the pawl from the cavities of the shaft.
The actuator includes a pair of ears and a slot formed between the ears for receiving the spring member and for preventing the spring member from moving laterally relative to the actuator.
Further objectives and advantages of the present invention will become apparent from a careful reading of a detailed description provided hereinbelow, with appropriate reference to accompanying drawings.